Robert Stone
Posts: 2
Nickname: ph4nt0m
Registered: Apr, 2005
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Re: How can I limit the number of characters entered into a JTextField?
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Posted: Apr 24, 2005 5:54 PM
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I got the answer. Thanks anyway.
Just incase anyone is curious this is the answer
The best way to do this is to subclass the JTextField class and then add a KeyListener to determine if you reached
the limit that will be passed in the constructor of the subclassed class.
import java.awt.event.*;
import java.awt.*;
import com.sun.java.swing.*;
public class SetLimit {
public static void main(String args[]) {
new SetLimitFrame();
}
}
class SetLimitFrame extends JFrame {
MyTextField mtf = new MyTextField(20,5);
SetLimitFrame() {
super();
/* Components should be added to the container's content pane */
Container cp = getContentPane();
/* Add the window listener */
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent evt) {
dispose(); System.exit(0);}});
cp.add(BorderLayout.NORTH,mtf);
/* Size the frame */
setSize(200,200);
/* Center the frame */
Dimension screenDim = Toolkit.getDefaultToolkit().getScreenSize();
Rectangle frameDim = getBounds();
setLocation((screenDim.width - frameDim.width) / 2,(screenDim.height - frameDim.height) / 2);
/* Show the frame */
setVisible(true);
}
}
class MyTextField extends JTextField
{
int limit;
MyTextField(int show,int limit)
{
super(show);
this.limit = limit;
addKeyListener(new KeyAdapter() {
public void keyTyped(KeyEvent evt) {
if (getText().length() >= MyTextField.this.limit)
evt.consume();}});
}
}
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